1. Field of the Invention
The present invention relates to an internal combustion engine. More particularly, the present invention relates to an oil separator for a four-cycle vertically-oriented engine.
2. Description of the Related Art
Internal combustion engines operating on a four-cycle principle may be provided with a pressure lubricating system for lubricating various engine components. In such engines, it is advantageous to provide a ventilating arrangement whereby the lubricant contained within a crankcase, oil pan and cam chamber may be ventilated to retard deterioration of the lubricant and to remove some of the contaminants from the lubricant. In some engines, a ventilating air source for the ventilation arrangement includes blow-by gases that may escape from the combustion chamber through the cylinder, past the piston, and into the crankcase.
Once present within the crankcase, the blow-by gases are circulated within portions of the lubrication system to ventilate the lubricant. As the blow-by gases pass through the lubrication system, lubricant may become entrained within the blow-by gases and be passed to the atmosphere as the blow-by gases are vented to the atmosphere through an outlet for the crankcase venting arrangement. Alternatively, the entrained lubricant may be cycled back through the induction system and into the combustion chamber for combustion with the air fuel charge. In either scenario, an undesirable level of hydrocarbon emissions may be conveyed to the atmosphere.
By positioning an outlet for the ventilating gases at a position outside of the crankcase, increased circulation of the ventilating gases may be obtained. Additionally, such positioning may allow for an increased vertical separation between the outlet and the lubricant pooling within a lubricant pan to ease the withdrawl of the ventilating air. For instance, positioning an outlet for the ventilating gases within a cam chamber would encourage the gases to pass from the crankcase into the cam chamber and increase the circulation path of the gases. Such movement of the gases, however, tends to oppose the movement of the lubricant and may result in additional lubricant becoming entrained within the ventilating air.
Accordingly, oil separators may be employed to remove some of the lubricant from the ventilating air prior to emission to the atmosphere or cycling through the induction system. In some engines, oil separators may be positioned external to the engine or abutting upon a wall of a head cover of the engine with an outlet duct positioned external to the crankcase in order to maintain the ventilation arrangement's outlet positioning. In engines featuring external oil separators, the provision of a separator component apart from the engine results in added complexity, weight, cost and bulk. Similarly, in engines featuring an adjoining oil separator, the number of parts is increased and the connection between the oil separator and the engine adds several assembly and maintenance difficulties. For instance, the juncture between the oil separator and the engine must be sealed, which adds components and, accordingly, weight to the engine. Moreover, the assembly becomes more difficult and costly due to the increase in parts. As will be recognized, the seal also may deteriorate over time, requiring replacement or maintenance to ensure proper oil separator and engine performance.